Researchers at the National Institutes of Health (NIH) have identified a novel opioid compound that could transform the treatment of pain and opioid use disorder. The findings, published in the journal Nature, demonstrate that the experimental drug delivers powerful pain relief in preclinical models without triggering major side effects typically associated with opioids.

The study, led by scientists at the National Institute on Drug Abuse (NIDA), explored a class of synthetic opioids known as nitazenes. While historically avoided due to their extreme potency, researchers engineered modified versions with improved safety profiles.

The team identified a compound known as DFNZ, derived from an earlier formulation (FNZ), which exhibited sustained analgesic effects without causing respiratory depression, tolerance, or significant withdrawal symptoms in laboratory animals. Notably, the drug maintained pain relief for up to two hours despite limited presence in the brain.

Unlike conventional opioids such as heroin or morphine, DFNZ demonstrated a lower potential for addiction. While test animals showed some drug-seeking behaviour, they quickly stopped when the drug was withdrawn—indicating weaker dependency patterns. Researchers attribute this to DFNZ’s unique neurochemical profile, which stimulates slower dopamine release without triggering the rapid surges linked to addiction.

Nora D. Volkow, Director of NIDA, said, “Developing a highly effective pain medication without the risk of addiction or overdose would have enormous public health benefits.” 

The compound also showed a favourable safety profile, with repeated dosing failing to produce tolerance or dependency. Importantly, it increased brain oxygen levels rather than suppressing respiration—a key risk factor in opioid-related fatalities.

The findings challenge long-standing assumptions about opioid pharmacology, suggesting that high-efficacy drugs targeting mu-opioid receptors can be developed safely. Researchers believe DFNZ could offer a new treatment approach not only for acute and chronic pain but also for opioid use disorder, potentially outperforming current therapies.

Further preclinical studies are planned to support regulatory approval for human trials. If successful, the drug could benefit a wide range of patients, including those undergoing surgery or suffering from chronic and cancer-related pain.